TROPICAL STORM FAY DISCUSSION NUMBER 10 - 颱風討論

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WTNT41 KNHC 180253
TCDAT1
TROPICAL STORM FAY DISCUSSION NUMBER 10
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL062008
1100 PM EDT SUN AUG 17 2008

AIR FORCE RECONNAISSANCE REPORTS NEAR 0000 UTC SHOWED LITTLE MOTION
SINCE THE EARLIER FIXES. RECENT SATELLITE IMAGERY AND CUBAN RADAR
DATA IMAGERY INDICATE THAT THE CENTER IS ILL-DEFINED AT THE
MOMENT...AND SURFACE SYNOPTIC DATA SUGGEST THAT THE CIRCULATION IS
SOMEWHAT ELONGATED FROM EAST TO WEST. STRONGEST CONVECTION IS
OCCURRING JUST TO THE EAST AND NORTHEAST OF THE ESTIMATED CENTER.
INITIAL MOTION IS A HIGHLY UNCERTAIN 305/9. THE TRACK FORECAST
REASONING IS NOT MUCH DIFFERENT FROM EARLIER TODAY. FAY IS LIKELY
TO TURN TOWARD THE NORTH ON THE WESTERN PERIPHERY OF A MID-LEVEL
RIDGE. NOAA G-IV JET DATA SHOW MID-TROPOSPHERIC HEIGHT FALLS OVER
THE SOUTHEASTERN GULF OF MEXICO WHICH ALSO SUPPORTS A TURN TOWARD
THE NORTH. SOME OF THE TRACK MODELS SUCH AS THE GFDL MODEL HAVE
SHIFTED...ONCE AGAIN...TO THE EAST. THERE HAVE OBVIOUSLY BEEN SOME
RUN-TO-RUN CONSISTENCY PROBLEMS WITH OUR TRACK GUIDANCE...BUT THIS
IS OFTEN THE CASE FOR WEAK TROPICAL CYCLONES IN THE MODEL INITIAL
CONDITIONS. I HAVE NOT MADE MUCH OF A CHANGE TO THE OFFICIAL
FORECAST WHICH REMAINS CLOSE TO THE DYNAMICAL MODEL CONSENSUS.

自從稍早的定位以來空軍偵察機於世界時0時報告顯示一點以的運動. 現在的衛星
影像和古巴的雷達資料表明出中心此刻已有清楚的輪廓...以及海面天氣資料推測
由東到西的環流有些細瘦. 強對流正發生於推測中心的東和東北部. 現時行徑非常
不明,可能是305度/9浬. 自從今日稍早已來路徑預報沒有多少變化. FAY有可能
在中層脊西側轉北. 本署的灣流五型噴射機資料展現出對流層中部高度在墨西哥
灣下降同樣地支持了這轉北的預測. 有些路徑模式像是GFDL已經轉變...在一次...
朝東. 明顯地我們的路徑預測一直有個別運算之間調諧上的問題...但這通常是
在現行條件中的模式對虛弱的熱帶氣旋作預測的實例. 我還沒對官方預報做出
太多改變,而且保持和動力模式共識一至.

WE HAVE BEEN CARRYING 45 KT FOR THE CURRENT INTENSITY SINCE EARLIER
TODAY ALTHOUGH THERE HAVE BEEN NO RECENTLY OBSERVED FLIGHT-LEVEL
WINDS TO SUPPORT THIS VALUE. HOWEVER IT IS BELIEVED THAT THESE
WINDS ARE LIKELY OCCURRING IN THE STRONG CONVECTION NORTHEAST OF
THE CENTER WHICH WAS NOT SAMPLED BY THE AIRCRAFT. AN UPPER-LEVEL
LOW OVER THE EXTREME NORTHWESTERN CARIBBEAN SEA IS IMPEDING THE
OUTFLOW OVER THE WESTERN PORTION OF THE TROPICAL CYCLONE AND MAY
EVEN BE CAUSING SOME UPPER-LEVEL CONVERGENCE OVER THE STORM. ON
THE OTHER HAND...THE SHIPS GUIDANCE INDICATES THAT VERTICAL SHEAR
WILL DECREASE DURING THE NEXT DAY OR SO. THEREFORE SOME
STRENGTHENING IS FORECAST WHILE FAY IS OVER WATER DURING THE
EARLIER PART OF THE FORECAST PERIOD. BY 48 HOURS OR SO...SHEAR
ASSOCIATED WITH AN UPPER-LEVEL TROUGH OVER THE EXTREME EASTERN GULF
OF MEXICO IS FORECAST TO INCREASE...AND THIS SHOULD LIMIT
INTENSIFICATION. THE OFFICIAL INTENSITY FORECAST IS A BLEND OF THE
LATEST GFDL AND HWRF MODEL PREDICTIONS. IT SHOULD BE ADDED THAT
THERE IS LOW CONFIDENCE IN THIS FORECAST HOWEVER.

自從今日稍早以來我們一直以四十五節做現時的強度,即使現在尚未有觀察的高度風
資料支持此數據. 無論如何我們相信這風速可能發生在地方偵查機還沒偵測到的
中心東北側的強對流.一個在加勒比海極西北側的高層低壓妨礙熱帶氣旋西部流場,
也可能剛好造成一些風暴的高層幅合. 另一方面...SHIPS推測指出一兩日後垂直風切
將會減弱. 除此以外預報稍早的部分中當FAY位於水域時有增強的預報. 大約四十八
小時或之後... 預報風切和位於墨西哥灣極東的高空槽的供伴會增強...這應該會限制
氣旋的增強. 官方的強度預報是最新的GFDL和HWRF模式預報的混合. 無論如何這應
該要注意這預測有低可性度在的.

IT IS IMPORTANT NOT TO FOCUS ON THE EXACT FORECAST TRACK. A BETTER
WAY OF ASSESSING YOUR RISK IS TO MAKE USE OF THE WIND SPEED
PROBABILITIES. THESE DO NOT CHANGE SIGNIFICANTLY FOR GIVEN
LOCATIONS WHEN SMALL ADJUSTMENTS ARE MADE TO THE TRACK FORECAST.

重要的是別太關注於路徑預報的精確度. 能評估你的風險最好的方法是使用
風速機率表. 當對路徑預報做出小小的修正時不會對位置做出值得注意的改變.



XHWA CRRT PWEN EGPD

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